1. Field of the Invention
The present invention concerns a method and apparatus for analyzing the operation of the electronic ignition of an internal combustion engine.
2. Description of Related Art
Electronic means for testing the performance on an internal combusion engine may be connected separately to corresponding connection clamps of the motor vehicle, or jointly connected to the vehicle by means of a diagnostic plug. Such an apparatus may be used to perform a number of diagnostic routines, for instance measuring engine speed, the timing angle, the ignition voltage, the time-function of the ignition voltage, the behaviour of the exhaust gas, the partial vacuum, etc. The ignition voltages of individual cylinders may be analyzed with an oscilloscope to determine the variation in voltage over time. The oscilloscope images enable an experienced user to ascertain the ignition voltage, the combustion voltage, the duration of combustion, the timing angle and the cam angle of an ignition system. The user may easily ascertain deviations from a predetermined value caused by, for example, an ignition voltage failure in a particular cylinder. This method, however, is limited to observing periodically reoccurring events that are present in each of a series of rapidly changing oscilloscope display screens. Nevertheless, an experienced user may determine the cause of ignition failure from the deviating ignition voltage plot.
Known engine testers, however, are incapable of detecting transient deviations of the ignition voltage. Such deviations manifest themselves, for instance, by occasional unbalanced operation or shaking of an idling engine.